Diaphragm Pumps with Chamber Crossventing

ABSTRACT

Illustrative embodiments of diaphragm pumps with chamber crossventing, and methods of operating such pumps, are disclosed. In at least one illustrative embodiment, a method of operating a diaphragm pump may comprise communicating compressed fluid from a compressed fluid inlet to a first motive fluid chamber to cause first and second diaphragms to move to a first end-of-stroke position, communicating compressed fluid from the first motive fluid chamber to a second motive fluid chamber while the first and second diaphragms are in the first end-of-stroke position, communicating compressed fluid from the compressed fluid inlet to the second motive fluid chamber to cause the first and second diaphragms to move to a second end-of-stroke position, and communicating compressed fluid from the second motive fluid chamber to the first motive fluid chamber while the first and second diaphragms are in the second end-of-stroke position.

CROSS REFERENCE TO RELATED APPLICATIONS

This application claims the benefit of U.S. Provisional Patent Application No. 61/839,703, filed Jun. 26, 2013, and U.S. Provisional Patent Application No. 61/895,796, filed Oct. 25, 2013 (both entitled “Energy Efficiency Enhancements for Air Operated Diaphragm Pumps”). The entire disclosures of both of the foregoing applications are incorporated by reference herein.

TECHNICAL FIELD

The present disclosure relates, generally, to diaphragm pumps and, more particularly, to diaphragm pumps with chamber crossventing.

BACKGROUND

Double diaphragm pumps alternately pressurize and exhaust two opposing motive fluid chambers to deliver pumped media during each stroke of the pump. Pressurizing the motive fluid chambers often results in operating efficiency losses as some of the motive fluid communicated to the chambers during each stroke does not contribute to the pumping action. In an attempt to mitigate this shortcoming, some prior pumps have interrupted the supply of motive fluid part of the way through each stroke to minimize the amount of motive fluid that does not contribute to the pumping action. Such pumps, however, may have limited utility in applications where it is desirable for the pump to have access to the energy of the motive fluid source throughout each stroke (e.g., when pumping media at higher head pressures).

SUMMARY

According to one aspect, a diaphragm pump may comprise a housing defining a first cavity and a second cavity, a first diaphragm disposed in the first cavity to separate the first cavity into a first motive fluid chamber and a first pumped media chamber, a second diaphragm disposed in the second cavity to separate the second cavity into a second motive fluid chamber and a second pumped media chamber, a shaft coupled between the first and second diaphragms and configured to move reciprocally with the first and second diaphragms between a first end-of-stroke position and a second end-of-stroke position, a main valve fluidly coupled between a compressed fluid inlet and the first and second motive fluid chambers, and a crossvent valve fluidly coupled between the first and second motive fluid chambers. The main valve may be movable between (i) a first position in which the main valve is configured to communicate compressed fluid from the compressed fluid inlet to the first motive fluid chamber and (ii) a second position in which the main valve is configured to communicate compressed fluid from the compressed fluid inlet to the second motive fluid chamber. The crossvent valve may be configured to (i) communicate compressed fluid between the first and second motive fluid chambers during a time period when the main valve is between the first and second positions and (ii) resist communication of compressed fluid between the first and second motive fluid chambers when the main valve is in either of the first and second positions.

In some embodiments, the main valve may be configured to resist communication of compressed fluid from the compressed fluid inlet to the first and second motive fluid chambers during the time period. The second motive fluid chamber may be fluidly coupled to an exhaust chamber when the main valve is in the first position, and the first motive fluid chamber may be fluidly coupled to the exhaust chamber when the main valve is in the second position. In some embodiments, the first and second motive fluid chambers are not fluidly coupled to the exhaust chamber during the time period.

In some embodiments, the diaphragm pump may further comprise a pilot valve configured to selectively communicate compressed fluid from the compressed fluid inlet to a pilot chamber of the main valve to control movement of the main valve between the first and second positions. The pilot valve may be further configured to selectively communicate compressed fluid from the compressed fluid inlet to a pilot chamber of the crossvent valve to cause the crossvent valve to communicate compressed fluid between the first and second motive fluid chambers during the time period.

In some embodiments, the crossvent valve may comprise a spool extending into the first motive fluid chamber such that the spool is configured to be actuated by the first diaphragm when in the first end-of-stroke position to cause the crossvent valve to communicate compressed fluid between the first and second motive fluid chambers. The spool of the crossvent valve may also extend into the second motive fluid chamber such that the spool is also configured to be actuated by the second diaphragm when in the second end-of-stroke position to cause the crossvent valve to communicate compressed fluid between the first and second motive fluid chambers. The spool of the crossvent valve may be biased toward a position in which the crossvent valve resists communication of compressed fluid between the first and second motive fluid chambers when the first and second diaphragms are between the first and second end-of-stroke positions.

According to another aspect, a diaphragm pump may comprise a housing defining a first cavity and a second cavity, a first diaphragm disposed in the first cavity to separate the first cavity into a first motive fluid chamber and a first pumped media chamber, a second diaphragm disposed in the second cavity to separate the second cavity into a second motive fluid chamber and a second pumped media chamber, a shaft coupled between the first and second diaphragms and configured to move reciprocally with the first and second diaphragms between a first end-of-stroke position and a second end-of-stroke position, and a main valve fluidly coupled between a compressed fluid inlet and the first and second motive fluid chambers. The main valve may be movable between (i) a first position in which the main valve is configured to communicate compressed fluid from the compressed fluid inlet to the first motive fluid chamber, (ii) a second position in which the main valve is configured to communicate compressed fluid from the compressed fluid inlet to the second motive fluid chamber, and (iii) a third position in which the main valve is configured to communicate compressed fluid between the first and second motive fluid chambers, the third position being between the first and second positions.

In some embodiments, the main valve may be configured to resist communication of compressed fluid between the first and second motive fluid chambers when the main valve is in either of the first and second positions. The main valve may be configured to resist communication of compressed fluid from the compressed fluid inlet to the first and second motive fluid chambers when the main valve is in the third position. The second motive fluid chamber may be fluidly coupled to an exhaust chamber when the main valve is in the first position, and the first motive fluid chamber may be fluidly coupled to the exhaust chamber when the main valve is in the second position. In some embodiments, the first and second motive fluid chambers are not fluidly coupled to the exhaust chamber when the main valve is in the third position.

In some embodiments, the diaphragm pump may further comprise a pilot valve configured to selectively communicate compressed fluid from the compressed fluid inlet to a pilot chamber of the main valve to control movement of the main valve between the first and second positions. The diaphragm pump may further comprise a flow control valve configured to control a flow rate of the compressed fluid communicated to the pilot chamber of the main valve to control a speed at which the main valve moves between the first and second positions.

According to yet another aspect, a method of operating a diaphragm pump may comprise communicating compressed fluid from a compressed fluid inlet to a first motive fluid chamber to cause first and second diaphragms to move to a first end-of-stroke position, communicating compressed fluid from the first motive fluid chamber to a second motive fluid chamber while the first and second diaphragms are in the first end-of-stroke position, communicating compressed fluid from the compressed fluid inlet to the second motive fluid chamber to cause the first and second diaphragms to move to a second end-of-stroke position, and communicating compressed fluid from the second motive fluid chamber to the first motive fluid chamber while the first and second diaphragms are in the second end-of-stroke position.

In some embodiments, compressed fluid is not communicated from the compressed fluid inlet to either of the first and second motive fluid chambers while compressed fluid is being communicated between the first and second motive fluid chambers. The method may further comprise fluidly coupling the second motive fluid chamber to an exhaust chamber while communicating compressed fluid from the compressed fluid inlet to the first motive fluid chamber. The method may further comprise fluidly coupling the first motive fluid chamber to the exhaust chamber while communicating compressed fluid from the compressed fluid inlet to the second motive fluid chamber. In some embodiments, the first and second motive fluid chambers are not fluidly coupled to the exhaust chamber while compressed fluid is being communicated between the first and second motive fluid chambers.

In some embodiments, shifting a main valve of the diaphragm pump to a first position may cause compressed fluid to be communicated from the compressed fluid inlet to the first motive fluid chamber, shifting the main valve to a second position may cause compressed fluid to be communicated from the compressed fluid inlet to the second motive fluid chamber, and compressed fluid may be communicated between the first and second motive fluid chambers while the main valve is shifting between the first and second positions. Compressed fluid may be communicated from the compressed fluid inlet to the first motive fluid chamber until the first and second diaphragms reach the first end-of-stroke position, and compressed fluid may be communicated from the compressed fluid inlet to the second motive fluid chamber until the first and second diaphragms reach the second end-of-stroke position.

BRIEF DESCRIPTION OF THE DRAWINGS

The concepts described in the present disclosure are illustrated by way of example and not by way of limitation in the accompanying figures. For simplicity and clarity of illustration, elements illustrated in the figures are not necessarily drawn to scale. For example, the dimensions of some elements may be exaggerated relative to other elements for clarity. Further, where considered appropriate, reference labels may be repeated among the figures to indicate corresponding or analogous elements.

FIG. 1 is a front perspective view of one illustrative embodiment of a double diaphragm pump;

FIG. 2 is a cross-sectional view of the pump of FIG. 1, taken along the line 2-2 in FIG. 1;

FIG. 3 is a table showing various operating stages of the pump of FIG. 1;

FIGS. 4A-4C are block diagrams illustrating various flow paths of compressed fluid through the pump of FIG. 1 during several of the operating stages of FIG. 3;

FIG. 5 is a diagrammatic view of the pump of FIG. 1 during one of the operating stages of FIG. 3;

FIG. 6 is a diagrammatic view of the pump of FIG. 1 during another of the operating stages of FIG. 3;

FIG. 7 is a diagrammatic view of the pump of FIG. 1 during yet another of the operating stages of FIG. 3;

FIG. 8 is a diagrammatic view of another illustrative embodiment of a double diaphragm pump during one operating stage;

FIG. 9 is a diagrammatic view of the pump of FIG. 8 during another operating stage;

FIG. 10 is a diagrammatic view of the yet another illustrative embodiment of a double diaphragm pump during one operating stage; and

FIG. 11 is a diagrammatic view of the pump of FIG. 10 during another operating stage.

DETAILED DESCRIPTION OF THE DRAWINGS

While the concepts of the present disclosure are susceptible to various modifications and alternative forms, specific exemplary embodiments thereof have been shown by way of example in the drawings and will herein be described in detail. It should be understood, however, that there is no intent to limit the concepts of the present disclosure to the particular forms disclosed, but on the contrary, the intention is to cover all modifications, equivalents, and alternatives falling within the spirit and scope of the present disclosure.

Referring now to FIGS. 1 and 2, one illustrative embodiment of a diaphragm pump 10 is shown. The pump 10 of FIGS. 1 and 2 is illustratively embodied as an air-operated double diaphragm pump. It is contemplated that, in other embodiments, the pump 10 might be embodied as another type of diaphragm pump (or even another type of positive displacement pump). In the illustrative embodiment, the pump 10 has a housing 12 that defines a cavity 14 and a cavity 16. The housing 12 is illustratively comprised of three sections coupled together by fasteners. As best seen in FIG. 2, the cavities 14, 16 of the pump 10 are each separated by a respective flexible diaphragm 18, 20 into a respective pumped media chamber 22, 24 and a respective motive fluid chamber 26, 28. The diaphragms 18, 20 are interconnected by a shaft 30, such that when the diaphragm 18 is moved to increase the volume of the associated pumped media chamber 22, the other diaphragm 20 is simultaneously moved to decrease the volume of the associated pumped media chamber 24, and vice versa.

The shaft 30 illustrated in FIG. 2 is a reciprocating diaphragm link rod having a fixed length, such that the diaphragms 18, 20 move reciprocally together with the shaft 30. The shaft 30 and diaphragms 18, 20 move back and forth a fixed distance that defines a stroke. The fixed distance is determined by the geometry of the pump 10, the shaft 30, the diaphragms 18, 20, and other components of the pump 10. A stroke is defined as the travel path of the shaft 30 between end-of-stroke positions. Movement of the shaft 30 from one end-of-stroke position to the other end-of-stroke position and back defines a cycle of operation of the shaft 30 (i.e., a cycle includes two consecutive strokes).

The pump 10 includes an inlet 32 for the supply of a compressed fluid (e.g., compressed air, another pressurized gas, hydraulic fluid, etc.) and a main valve 34 for alternately supplying the compressed fluid to the motive fluid chambers 26, 28 to drive reciprocation of the diaphragms 18, 20 and the shaft 30. The main valve 34 is fluidly coupled between the inlet 32 and the motive fluid chambers 26, 28. When the main valve 34 supplies compressed fluid to the motive fluid chamber 26 (while in a position 60), the main valve 34 places an exhaust assembly 36 in communication with the other motive fluid chamber 28 to permit fluid to be expelled therefrom. Conversely, when the main valve 34 supplies compressed fluid to the motive fluid chamber 28 (while in a position 61), the main valve 34 places the motive fluid chamber 26 in communication with the exhaust assembly 36. In the illustrative embodiment of the pump 10, movement of the main valve 34 between the positions 60, 61 is controlled by a pilot valve 35 (shown diagrammatically in FIGS. 5-7). As such, by controlling movement of the main valve 34, the pilot valve 35 of the pump 10 controls the supply of compressed fluid to the motive fluid chambers 26, 28.

As seen in FIGS. 5-7, the pilot valve 35 is illustratively embodied as a directional control valve having a spool 42 movable between a plurality of positions to selectively fluidly couple a plurality of ports formed in the pilot valve 35 to one another. The pilot valve 35 is positioned between the cavities 14, 16 such that the spool 42 extends into each of the cavities 14, 16, as shown in FIGS. 5-7. As the diaphragms 18, 20 move in unison with the shaft 30 between the end-of-stroke positions, the diaphragms alternately contact the spool 42, causing the spool 42 to move between its positions such that the pilot valve 35 either communicates compressed fluid to a pilot chamber 76 of the main valve 34 or exhausts the pilot chamber 76 to the exhaust assembly 36.

The exhaust assembly 36 of the pump 10 includes an exhaust chamber 50 and a muffler 52 that is received in the exhaust chamber 50. In the illustrative embodiment, the main valve 34 alternately couples one of the motive fluid chambers 26, 28 (whichever of the motive fluid chambers 26, 28 is not being supplied with compressed fluid by the main valve 34) to the exhaust assembly 36 to allow any fluid in that motive fluid chamber 26, 28 to be vented to the atmosphere. It is contemplated that, in other embodiments, the pump 10 might use other mechanisms to selectively couple the motive fluid chambers 26, 28 to the exhaust assembly 36 (e.g., “quick dump check valves” positioned between the main valve 34 and the motive fluid chambers 26, 28).

During operation of the pump 10, as the main valve 34, the pilot valve 35, and the exhaust assembly 36 cooperate to effect the reciprocation of the diaphragms 18, 20 and the shaft 30, the pumped media chambers 22, 24 alternately expand and contract to create respective low and high pressure within the respective pumped media chambers 22, 24. The pumped media chambers 22, 24 each communicate with a pumped media inlet 38 that may be connected to a source of fluid to be pumped (also referred to herein as “pumped media”) and also each communicate with a pumped media outlet 40 that may be connected to a receptacle for the fluid being pumped. Check valves (not shown) ensure that the fluid being pumped moves only from the pumped media inlet 38 toward the pumped media outlet 40. For instance, when the pumped media chamber 22 expands, the resulting negative pressure draws fluid from the pumped media inlet 38 into the pumped media chamber 22. Simultaneously, the other pumped media chamber 24 contracts, which creates positive pressure to force fluid contained therein to the pumped media outlet 40. Subsequently, as the shaft 30 and the diaphragms 18, 20 move in the opposite direction, the pumped media chamber 22 will contract and the pumped media chamber 24 will expand (forcing fluid contained in the pumped media chamber 24 to the pumped media outlet 40 and drawing fluid from the pumped media inlet 38 into the pumped media chamber 24).

Referring now to FIG. 3, various operating stages of the pump 10 achieved as the shaft 30 completes a cycle (i.e., as the shaft 30 moves from one end-of-stroke position to the other end-of-stroke position and back) are shown as a table. In the “Begin Left Stroke” stage 55, compressed fluid is supplied from the main valve 34 to the motive fluid chamber 26 (i.e., the left chamber) to pressurize the motive fluid chamber 26, and any fluid contained in the motive fluid chamber 28 (i.e., the right chamber) is contemporaneously vented to the exhaust assembly 36. In the “End Left Stroke” stage 54, the motive fluid chambers 26, 28 are fluidly coupled to one another, thereby permitting compressed fluid to flow from the motive fluid chamber 26 to the motive fluid chamber 28. In the “Begin Right Stroke” stage 57, compressed fluid is supplied from the main valve 34 to the motive fluid chamber 28 to pressurize the motive fluid chamber 28, and any fluid contained in the motive fluid chamber 26 is contemporaneously vented to the exhaust assembly 36. In the “End Right Stroke” stage 58, the motive fluid chambers 26, 28 are fluidly coupled to one another, thereby permitting compressed fluid to flow from the motive fluid chamber 28 to the motive fluid chamber 26.

Various flow paths of compressed fluid through the pump 10 during the “Begin Left Stroke” stage 55, the “End Left Stroke” stage 54, and the “Begin Right Stroke” stage 57 are illustrated in FIGS. 4A-4C, respectively, in greater detail. It will be appreciated that, with respect to the block diagrams of FIGS. 4A-4C, the “End Right Stroke” stage 58 is substantially similar to the “End Left Stroke” stage 54 shown in FIG. 4B and discussed below. As such, the “End Right Stroke” stage 58 will not be separately described below. In each of FIGS. 4A-4C, the flow path(s) of compressed fluid through the pump 10 are shown by the connections of heavier weight.

Referring now to FIG. 4A, the flow path of compressed fluid through the pump 10 in the “Begin Left Stroke” stage 55 is shown as a block diagram. Compressed fluid is communicated to one or more supply valves from a compressed fluid source. In the pump 10, the one or more supply valves are illustratively embodied in the single main valve 34. However, in other embodiments, multiple supply valves may be used. Compressed fluid is supplied by the main valve 34 to the motive fluid chamber 26 (i.e., the left motive fluid chamber) when the main valve 34 is in the position 60 to cause the shaft 30 to move toward the diaphragm 18. At the same time, any fluid contained in the motive fluid chamber 28 (i.e., the right motive fluid chamber) is vented through one or more exhaust valves to the atmosphere. In the pump 10, the one or more exhaust valves are illustratively embodied in the single main valve 34. However, in other embodiments, multiple exhaust valves separate from the supply valve(s) may be used.

The pump 10 illustratively includes a crossvent valve 56 fluidly coupled between the motive fluid chambers 26, 28, as suggested in FIG. 4A. As shown in FIG. 4B (and FIG. 6), the crossvent valve 56 is configured to communicate compressed fluid between the motive fluid chambers 26, 28 during a time period when the main valve 34 is between the two positions 60, 61. In addition, the crossvent valve 56 is configured to resist communication of compressed fluid between the motive fluid chambers 26, 28 when the main valve 34 is in either the position 60 or the position 61. As shown in FIG. 4A, the crossvent valve 56 resists the flow of compressed fluid between the motive fluid chambers 26, 28 during the “Begin Left Stroke” stage 55.

Referring now to FIG. 4B, the flow path of compressed fluid through the pump 10 in the “End Left Stroke” stage 54 is shown as a block diagram. The main valve 34 is between the position 60 and the position 61, and the crossvent valve 56 fluidly couples the motive fluid chambers 26, 28 to one another. Compressed fluid is communicated from the motive fluid chamber 26 to the motive fluid chamber 28 through the crossvent valve 56. In comparison, during the “End Right Stroke” stage 58 (see FIG. 6), compressed fluid is communicated from the motive fluid chamber 28 to the motive fluid chamber 26 through the crossvent valve 56. During both the “End Left Stroke” stage 54 and the “End Right Stroke” stage 58, the motive fluid chambers 26, 28 are disconnected from both the compressed fluid source and the exhaust.

Referring now to FIG. 4C, the flow path of compressed fluid through the pump 10 in the “Begin Right Stroke” stage 57 is shown as a block diagram. Compressed fluid is communicated to the main valve 34 from the compressed fluid source, and compressed fluid is supplied by the main valve 34 to the motive fluid chamber 28 when the main valve 34 is in the position 61 to cause the shaft 30 to move toward the diaphragm 20. At the same time, any fluid contained in the motive fluid chamber 26 is exhausted to the atmosphere. As shown in FIG. 4C, the crossvent valve 56 resists the flow of compressed fluid between the motive fluid chambers 26, 28 during the “Begin Right Stroke” stage 57.

Referring generally now to FIGS. 5-7, diagrammatic views of the pump 10 during the “Begin Right Stroke” stage 57, the “End Right Stroke” stage 58, and the “Begin Left Stroke” stage 55 are shown, respectively. Fluid connections between components included in the pump 10 are generally depicted by lines, and the directions of compressed fluid flow between the components of the pump 10 are generally indicated by arrowheads on those lines.

As seen in FIG. 5, the main valve 34 supplies compressed fluid to the motive fluid chamber 28 during the “Begin Right Stroke” stage 57. Specifically, compressed fluid is communicated from the inlet 32 to a port 62 of the main valve 34 via a conduit 64, from the port 62 to a port 66 of the main valve 34 fluidly coupled to the port 62, and from the port 66 to the motive fluid chamber 28 via a conduit 69. Additionally, the main valve 34 vents any fluid contained in the motive fluid chamber 26 to the exhaust assembly 36 during the “Begin Right Stroke” stage 57. Specifically, fluid is communicated from the motive fluid chamber 26 to a port 68 of the main valve 34 via a conduit 71, from the port 68 to a port 70 of the main valve 34 fluidly coupled to the port 68, and from the port 70 to the exhaust assembly 36 via a conduit 72.

The main valve 34 is shown (diagrammatically) in position 61 in FIG. 5. When the main valve 34 is in the position 61 (as well as the position 60 and all other positions of the main valve 34 between the two positions 60, 61), compressed fluid is communicated from the inlet 32 to a pressure chamber 74 of the main valve 34 via conduits 75, 77. Compressed fluid is illustratively communicated to the pressure chamber 74 at a constant pressure. A pressure regulator (not shown) may be fluidly coupled between the inlet 32 and the pressure chamber 74 to regulate the compressed fluid communicated to the pressure chamber 74 to the constant pressure. In some embodiments, the constant pressure supplied to the pressure chamber 74 is of a smaller magnitude than the compressed fluid pressure supplied by the inlet 32. In other embodiments, compressed fluid at a variable pressure may be communicated to the pressure chamber 74. In any case, the pilot chamber 76 of the main valve 34 positioned opposite the pressure chamber 74 is fluidly coupled to the exhaust assembly 36 in the position 61 to communicate compressed fluid contained in the pilot chamber 76 to the exhaust assembly 36 as shown in FIG. 5 (e.g., so the compressed fluid pressure in the pilot chamber 76 is approximately at atmospheric pressure). Specifically, compressed fluid in the pilot chamber 76 is communicated to a port 79 of the pilot valve 35 via conduits 78, 80, from the port 79 to a port 81 of the pilot valve 35 fluidly coupled to the port 79, and from the port 81 to the exhaust assembly 36 via conduits 83, 72. The pilot valve 35 is used to control the pressure differential between the pressure chamber 74 and the pilot chamber 76 of the main valve 34 to cause the main valve 34 to move between the two positions 60, 61.

The spool 42 of the pilot valve 35 extends into each of the motive fluid chambers 26, 28, as shown in FIG. 5. The spool 42 of the pilot valve 35 is spaced apart from each of the diaphragms 18, 20 such that the port 79 is fluidly coupled to the port 81 and such that communication between a port 84 of the pilot valve 35 and the port 79 is resisted. The port 84 receives compressed fluid from the inlet 32 via conduits 75, 85, 87. As shown in FIG. 5, the pilot valve 35 fluidly couples the pilot chamber 76 to atmospheric pressure. As best seen in FIGS. 6-7, the pilot valve 35 fluidly couples the pilot chamber 76 to compressed fluid pressure communicated to the port 84 when the main valve 34 is between the two positions 60, 61 and when the main valve 34 is in the position 60.

The crossvent valve 56 is fluidly coupled to the motive fluid chambers 26, 28 via conduits 93, 95, respectively, as shown in FIG. 5. A pressure chamber 86 of the crossvent valve 56 is fluidly coupled to the port 84 of the pilot valve 35 via a conduit 89. A pilot chamber 88 of the crossvent valve 56 positioned opposite the pressure chamber 86 is fluidly coupled to the port 79 of the pilot valve 35 via a conduit 91. The pressure differential between the pressure chamber 86 and the pilot chamber 88 substantially mirrors the pressure differential between the pressure chamber 74 and the pilot chamber 76 of the main valve 34. As such, by controlling the pressure differential between the pressure chamber 74 and the pilot chamber 76, the pilot valve 35 effectively synchronizes the operation of the crossvent valve 56 with the main valve 34.

During the operating stage of the pump 10 shown in FIG. 5, the pressure differential between the pressure chamber 74 and the pilot chamber 76 exceeds a first threshold. As a result, the compressed fluid pressure communicated to the pressure chamber 74 causes the main valve 34 to move to the position 61, thereby causing compressed fluid to be supplied from the main valve 34 to the motive fluid chamber 28 as indicated above. Compressed fluid supplied to the motive fluid chamber 28 flows to the crossvent valve 56 via the conduit 95 (i.e., as shown by arrows 97). Similar to the main valve 34, the pressure differential between the pressure chamber 86 and the pilot chamber 88 exceeds a second threshold that may be approximately equal to the first threshold. As a result, the compressed fluid pressure communicated to the pressure chamber 86 causes the crossvent valve 56 to resist communication of compressed fluid between the motive fluid chambers 26, 28 via the conduits 93, 95.

FIG. 6 diagrammatically illustrates the pump 10 in the “End Right Stroke” stage 58, in which the main valve 34 is in a position 63 that is between the two positions 60, 61. As described in more detail below, the main valve 34 resists communication of compressed fluid from the inlet 32 to each of the motive fluid chambers 26, 28 when the main valve 34 is in the position 63.

The shaft 30 reaches the end-of-stroke position shown in FIG. 6 (i.e., the right end-of-stroke position) when the diaphragm 18 contacts the pilot valve 35. In response to being contacted by the diaphragm 18, the pilot valve 35 fluidly couples the port 84 to the port 79. Compressed fluid is thereby communicated to the port 84 from the inlet 32, and from the port 84 to the pilot chamber 76 via the port 79 and conduits 78, 80 as shown in FIG. 6. Because the pilot chamber 76 is fluidly coupled to compressed fluid pressure from the inlet 32, the pressure differential between the pilot chamber 76 and the pressure chamber 74 in FIG. 6 is different than the pressure differential in FIG. 5. Specifically, the pressure differential between the pilot chamber 76 and the pressure chamber 74 in FIG. 6 falls below the first threshold. As a result, the compressed fluid pressure supplied to the pilot chamber 76 urges the main valve 34 into the position 63 (i.e., away from the position 61 and toward the position 60).

The position 63 of the main valve 34 (shown diagrammatically in FIG. 6) is one illustrative position of a plurality of positions achieved by the main valve 34 during a time period when the main valve 34 moves between the two positions 60, 61. In the position 63, the main valve 34 fluidly de-couples each of the ports 62, 66, 68, 70 from one another, as shown in FIG. 6. The main valve 34 resists communication of compressed fluid from the inlet 32 to each of the motive fluid chambers 26, 28 during the time period as indicated above. Additionally, the main valve 34 resists communication of compressed fluid from the motive fluid chambers 26, 28 to the exhaust assembly 36 during the time period.

The compressed fluid pressure communicated to the pilot chamber 76 of the main valve 34 is also communicated to the pilot chamber 88 of the crossvent valve 56 via the conduit 91, as shown in FIG. 6. As such, the pressure differentials between the pilot chamber 76/pressure chamber 74 and the pilot chamber 88/pressure chamber 86 are approximately equal to one another, and the pressure differential between the pilot chamber 88 and the pressure chamber 86 falls below the second threshold. The compressed fluid pressure from the pilot chamber 76 causes the crossvent valve 56 to communicate compressed fluid (see the arrows 97) between the motive fluid chambers 26, 28 via conduits 93, 95 as shown in FIG. 6.

As seen in FIG. 7, the main valve 34 supplies compressed fluid to the motive fluid chamber 26 during the “Begin Left Stroke” stage 55. Specifically, compressed fluid is communicated from the inlet 32 to the port 62 via the conduit 64, from the port 62 to the port 68 fluidly coupled to the port 62, and from the port 68 to the motive fluid chamber 26 via the conduit 71. Additionally, the main valve 34 vents any fluid contained in the motive fluid chamber 28 to the exhaust assembly 36 during the “Begin Left Stroke” stage 55. Specifically, fluid is communicated from the motive fluid chamber 28 to the port 66 via the conduit 69, from the port 66 to the port 70 fluidly coupled to the port 66, and from the port 70 to the exhaust assembly 36 via the conduit 72.

The main valve 34 is shown in the position 60 in FIG. 7. In the position 60, the pilot chamber 76 of the main valve 34 receives compressed fluid pressure from the inlet 32. Specifically, compressed fluid is communicated from the inlet 32 to the port 84 via conduits 75, 85, 87, from the port 84 to the port 79 fluidly coupled to the port 84, and from the port 79 to the pilot chamber 76 via conduits 78, 80.

During operation of the pump 10 as shown in FIG. 7, the pressure differential between the pressure chamber 74 and the pilot chamber 76 exceeds the first threshold. As a result, the compressed fluid pressure communicated to the pilot chamber 76 causes the main valve 34 to move to the position 60, thereby causing compressed fluid to be supplied from the main valve 34 to the motive fluid chamber 26 as indicated above. Compressed fluid supplied to the motive fluid chamber 26 flows to the crossvent valve 56 via the conduit 93 (i.e., as shown by arrows 99). Similar to the main valve 34, the pressure differential between the pressure chamber 86 and the pilot chamber 88 exceeds the second threshold. As a result, the compressed fluid pressure communicated to the pilot chamber 88 causes the crossvent valve 56 to resist communication of compressed fluid between the motive fluid chambers 26, 28 via the conduits 93, 95.

Referring now to FIGS. 8-9, a diaphragm pump 110 is shown that is similar in many respects to the pump 10 shown in FIGS. 1-7 and described above. Accordingly, similar reference numbers (in the 100 series in FIGS. 8-9) indicate features that are similar in structure and operation between the pump 110 and the pump 10. The description of the pump 10 is hereby incorporated by reference to apply to the pump 110, except in instances when it conflicts with the specific description and drawings of the pump 110.

As seen in FIGS. 8-9, the pilot valve 135 of the pump 110 is fluidly coupled between the inlet 132 and the main valve 134. In the “Begin Right Stroke” stage 157 shown in FIG. 8, the main valve 134 is in the position 161 such that compressed fluid communicated to the main valve 134 from the inlet 132 is supplied to the motive fluid chamber 128, and any fluid contained in the motive fluid chamber 126 is vented to an exhaust assembly 136 (like exhaust assembly 36) through the main valve 134. In the “End Right Stroke” stage 158 shown in FIG. 9, the main valve 134 is in the position 163 such that the main valve 134 resists communication of compressed fluid from the inlet 132 to the motive fluid chambers 126, 128 and resists communication of compressed fluid from the motive fluid chambers 126, 128 to the exhaust assembly 136.

In the position 161 shown in FIG. 8, the pilot chamber 176 of the main valve 134 is fluidly coupled to the exhaust assembly so that compressed fluid pressure in the pilot chamber 176 is approximately at atmospheric pressure. Specifically, compressed fluid in the pilot chamber 176 is communicated to the port 179 of the pilot valve 135 via conduit 198, from the port 179 to the port 181 fluidly coupled to the port 179, and from the port 181 to the exhaust assembly 136 via conduits 183, 172. In each of the positions 161, 163 of the main valve 134 shown in FIGS. 8-9, respectively, the port 184 of the pilot valve 135 receives compressed fluid from the inlet 132 via conduits 175, 196. In the position 163 of the main valve 134 shown in FIG. 9, the pilot valve 135 fluidly couples the pilot chamber 176 to compressed fluid pressure communicated to the port 184 from the inlet 132.

The pump 110 includes a crossvent valve 182 having a spool 167 extending into each of the motive fluid chambers 126, 128 as shown in FIGS. 8-9. The spool 167 is configured to be actuated by the diaphragm 118 when in the right end-of-stroke position to cause the crossvent valve 182 to communicate compressed fluid between the motive fluid chambers 126, 128. Additionally, the spool 167 is configured to be actuated by the diaphragm 120 when in the left end-of-stroke position to cause the crossvent valve 182 to communicate compressed fluid between the motive fluid chambers 126, 128.

The shaft 130 has not yet reached the right end-of-stroke position in FIG. 8, and as such, the crossvent valve 182 is spaced apart from the diaphragm 118. The spool 167 of the crossvent valve 182 is biased (e.g., pneumatically or mechanically) toward a position in which the crossvent valve 182 resists communication of compressed fluid between the motive fluid chambers 26, 28 (as shown in FIG. 8). When the spool 167 contacts the diaphragm 118, as shown in FIG. 9, the bias is overcome, and the crossvent valve 182 allows compressed fluid to flow between the motive fluid chambers 126, 128.

Referring now to FIGS. 10-11, a diaphragm pump 210 is shown that is similar in many respects to the pump 10 shown in FIGS. 1-7 and described above, as well as the pump 110 shown in FIGS. 8-9 and described above. Accordingly, similar reference numbers (in the 200 series in FIGS. 10-11) indicate features that are similar in structure and operation between the pumps 10, 110, 210. The descriptions of the pump 10 and the pump 110 are hereby incorporated by reference to apply to the pump 210, except in instances when it conflicts with the specific description and drawings of the pump 210.

The pump 210 shown in FIGS. 10-11 illustratively includes a main valve 237 that is substantially similar to the main valves 34, 134. However, unlike the main valves 34, 134, the main valve 237 is configured to move between the following positions: a position 260 (not shown) in which the main valve 237 communicates compressed fluid from the inlet 232 to the motive fluid chamber 226, a position 261 in which the main valve 237 communicates compressed fluid from the inlet 232 to the motive fluid chamber 228 (see FIG. 10), and a position 263 in which the main valve 237 communicates compressed fluid between the motive fluid chambers 226, 228 (see arrows 215 in FIG. 11). The position 263 of the main valve 134 is between the position 260 and the position 261.

The main valve 237 is fluidly coupled to the motive fluid chambers 226, 228 via conduits 211, 213, respectively. When the main valve 237 is in either the position 260 or the position 261, the main valve 237 resists communication between the motive fluid chambers 226, 228 via the conduits 211, 213. For example, as shown in FIG. 10, the main valve 237 resists communication of compressed fluid from the motive fluid chamber 228 to the motive fluid chamber 226 (see arrows 215) when the main valve 237 is in the position 261. Similar to the main valves 34, 134, when the main valve 237 is in the position 263, the main valve 237 resists communication of compressed fluid from the inlet 232 to the motive fluid chambers 226, 228 and from the motive fluid chambers 226, 228 to an exhaust assembly 236.

Referring to FIGS. 10-11, a flow control valve 259 (illustratively embodied as a needle valve) is fluidly coupled between the pilot chamber 276 and the pilot valve 235. The flow control valve 259 is configured to control the flow rate of compressed fluid communicated to the pilot chamber 276 to control a speed at which the main valve 237 moves between the position 260 and the position 261. As best seen in FIG. 11, compressed fluid is communicated from the inlet 232 to the conduit 298 through the pilot valve 235. The flow control valve 259 is configured to control the flow rate of compressed fluid flowing through the conduit 298 toward the pilot chamber 276. Compressed fluid flowing to the pilot chamber 276 causes the main valve 237 to move between the position 260 and the position 261 to the position 263. Therefore, by controlling the flow rate of compressed fluid to the pilot chamber 276, the flow control valve 259 controls the speed at which the main valve 237 moves between the position 260 and the position 261 (and, hence, the duration of such movement).

While certain illustrative embodiments have been described in detail in the figures and the foregoing description, such an illustration and description is to be considered as exemplary and not restrictive in character, it being understood that only illustrative embodiments have been shown and described and that all changes and modifications that come within the spirit of the disclosure are desired to be protected. There are a plurality of advantages of the present disclosure arising from the various features of the apparatus, systems, and methods described herein. It will be noted that alternative embodiments of the apparatus, systems, and methods of the present disclosure may not include all of the features described yet still benefit from at least some of the advantages of such features. Those of ordinary skill in the art may readily devise their own implementations of the apparatus, systems, and methods that incorporate one or more of the features of the present disclosure. 

1. A diaphragm pump comprising: a housing defining a first cavity and a second cavity; a first diaphragm disposed in the first cavity to separate the first cavity into a first motive fluid chamber and a first pumped media chamber; a second diaphragm disposed in the second cavity to separate the second cavity into a second motive fluid chamber and a second pumped media chamber; a shaft coupled between the first and second diaphragms and configured to move reciprocally with the first and second diaphragms between a first end-of-stroke position and a second end-of-stroke position; a main valve fluidly coupled between a compressed fluid inlet and the first and second motive fluid chambers, the main valve being movable between (i) a first position in which the main valve is configured to communicate compressed fluid from the compressed fluid inlet to the first motive fluid chamber and (ii) a second position in which the main valve is configured to communicate compressed fluid from the compressed fluid inlet to the second motive fluid chamber; and a crossvent valve fluidly coupled between the first and second motive fluid chambers, the crossvent valve being configured to (i) communicate compressed fluid between the first and second motive fluid chambers during a time period when the main valve is between the first and second positions and (ii) resist communication of compressed fluid between the first and second motive fluid chambers when the main valve is in either of the first and second positions.
 2. The diaphragm pump of claim 1, wherein the main valve is configured to resist communication of compressed fluid from the compressed fluid inlet to the first and second motive fluid chambers during the time period.
 3. The diaphragm pump of claim 1, wherein: the second motive fluid chamber is fluidly coupled to an exhaust chamber when the main valve is in the first position; the first motive fluid chamber is fluidly coupled to the exhaust chamber when the main valve is in the second position; and the first and second motive fluid chambers are not fluidly coupled to the exhaust chamber during the time period.
 4. The diaphragm pump of claim 1, further comprising a pilot valve configured to selectively communicate compressed fluid from the compressed fluid inlet to a pilot chamber of the main valve to control movement of the main valve between the first and second positions.
 5. The diaphragm pump of claim 4, wherein the pilot valve is further configured to selectively communicate compressed fluid from the compressed fluid inlet to a pilot chamber of the crossvent valve to cause the crossvent valve to communicate compressed fluid between the first and second motive fluid chambers during the time period.
 6. The diaphragm pump of claim 1, wherein the crossvent valve comprises a spool extending into the first motive fluid chamber such that the spool is configured to be actuated by the first diaphragm when in the first end-of-stroke position to cause the crossvent valve to communicate compressed fluid between the first and second motive fluid chambers.
 7. The diaphragm pump of claim 6, wherein the spool of the crossvent valve also extends into the second motive fluid chamber such that the spool is also configured to be actuated by the second diaphragm when in the second end-of-stroke position to cause the crossvent valve to communicate compressed fluid between the first and second motive fluid chambers.
 8. The diaphragm pump of claim 7, wherein the spool of the crossvent valve is biased toward a position in which the crossvent valve resists communication of compressed fluid between the first and second motive fluid chambers when the first and second diaphragms are between the first and second end-of-stroke positions.
 9. A diaphragm pump comprising: a housing defining a first cavity and a second cavity; a first diaphragm disposed in the first cavity to separate the first cavity into a first motive fluid chamber and a first pumped media chamber; a second diaphragm disposed in the second cavity to separate the second cavity into a second motive fluid chamber and a second pumped media chamber; a shaft coupled between the first and second diaphragms and configured to move reciprocally with the first and second diaphragms between a first end-of-stroke position and a second end-of-stroke position; and a main valve fluidly coupled between a compressed fluid inlet and the first and second motive fluid chambers, the main valve being movable between (i) a first position in which the main valve is configured to communicate compressed fluid from the compressed fluid inlet to the first motive fluid chamber, (ii) a second position in which the main valve is configured to communicate compressed fluid from the compressed fluid inlet to the second motive fluid chamber, and (iii) a third position in which the main valve is configured to communicate compressed fluid between the first and second motive fluid chambers, the third position being between the first and second positions.
 10. The diaphragm pump of claim 9, wherein the main valve is configured to resist communication of compressed fluid between the first and second motive fluid chambers when the main valve is in either of the first and second positions.
 11. The diaphragm pump of claim 9, wherein the main valve is configured to resist communication of compressed fluid from the compressed fluid inlet to the first and second motive fluid chambers when the main valve is in the third position.
 12. The diaphragm pump of claim 9, wherein: the second motive fluid chamber is fluidly coupled to an exhaust chamber when the main valve is in the first position; the first motive fluid chamber is fluidly coupled to the exhaust chamber when the main valve is in the second position; and the first and second motive fluid chambers are not fluidly coupled to the exhaust chamber when the main valve is in the third position.
 13. The diaphragm pump of claim 9, further comprising a pilot valve configured to selectively communicate compressed fluid from the compressed fluid inlet to a pilot chamber of the main valve to control movement of the main valve between the first and second positions.
 14. The diaphragm pump of claim 13, further comprising a flow control valve configured to control a flow rate of the compressed fluid communicated to the pilot chamber of the main valve to control a speed at which the main valve moves between the first and second positions.
 15. A method of operating a diaphragm pump comprising a housing defining a first cavity and a second cavity, a first diaphragm disposed in the first cavity to separate the first cavity into a first motive fluid chamber and a first pumped media chamber, a second diaphragm disposed in the second cavity to separate the second cavity into a second motive fluid chamber and a second pumped media chamber, a shaft coupled between the first and second diaphragms, and a compressed fluid inlet, the method comprising: communicating compressed fluid from the compressed fluid inlet to the first motive fluid chamber to cause the first and second diaphragms to move to a first end-of-stroke position; communicating compressed fluid from the first motive fluid chamber to the second motive fluid chamber while the first and second diaphragms are in the first end-of-stroke position; communicating compressed fluid from the compressed fluid inlet to the second motive fluid chamber to cause the first and second diaphragms to move to a second end-of-stroke position; and communicating compressed fluid from the second motive fluid chamber to the first motive fluid chamber while the first and second diaphragms are in the second end-of-stroke position.
 16. The method of claim 15, wherein compressed fluid is not communicated from the compressed fluid inlet to either of the first and second motive fluid chambers while compressed fluid is being communicated between the first and second motive fluid chambers.
 17. The method of claim 15, further comprising: fluidly coupling the second motive fluid chamber to an exhaust chamber while communicating compressed fluid from the compressed fluid inlet to the first motive fluid chamber; and fluidly coupling the first motive fluid chamber to the exhaust chamber while communicating compressed fluid from the compressed fluid inlet to the second motive fluid chamber.
 18. The method of claim 17, wherein the first and second motive fluid chambers are not fluidly coupled to the exhaust chamber while compressed fluid is being communicated between the first and second motive fluid chambers.
 19. The method of claim 15, wherein: shifting a main valve of the diaphragm pump to a first position causes compressed fluid to be communicated from the compressed fluid inlet to the first motive fluid chamber; shifting the main valve to a second position causes compressed fluid to be communicated from the compressed fluid inlet to the second motive fluid chamber; and compressed fluid is communicated between the first and second motive fluid chambers while the main valve is shifting between the first and second positions.
 20. The method of claim 15, wherein: compressed fluid is communicated from the compressed fluid inlet to the first motive fluid chamber until the first and second diaphragms reach the first end-of-stroke position; and compressed fluid is communicated from the compressed fluid inlet to the second motive fluid chamber until the first and second diaphragms reach the second end-of-stroke position. 